Alex Karpovsky owes Lena Dunham big time. Without her, he would probably be just another struggling actor-filmmaker in the crowded indie marketplace. With her — and her HBO show, “Girls” (he plays Ray, the barrista) — he’s part of a cultural juggernaut.

And without her, it’s hard to imagine that “Rubberneck” and “Red Flag,” two wispy, downbeat movies that he directed and wrote (“Rubberneck” with Garth Donovan), would rate a double feature at the Elinor Bunin Munroe Film Center.

Though “Red Flag” is a comedy and “Rubberneck” a would-be psychosexual thriller, the movies have plenty in common, from their indifferent visual aesthetics to their low-wattage absorption in the problems of failed romance.

In “Rubberneck” Mr. Karpovsky plays Paul, a lab technician who has a fling with a colleague (Jaime Ray Newman). When she ditches him, he obsesses about her in ways that seem normal until they become destructive and then violent.

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Alex Karpovsky discusses his leading roles in the thriller “Rubberneck,” which he also directed, and the comedy “Supporting Characters.” Both films played at the Tribeca Film Festival in 2012.CreditCreditGarth Donovan

Mr. Karpovsky makes Paul creepy enough, and there’s something interesting in the idea of how close Woody Allen-type sexual neurosis might be to psychosis. How close is the sad-sack Paul to Norman Bates?

“Rubberneck,” though, is too limp and lacking in texture to give those questions dramatic shape, much less earn the title of thriller. It’s dragged down by non-scene after non-scene, and filmmaking choices that don’t earn their keep.

The story takes place in Boston, but this textureless place could be Any City, U.S.A., just as the lab where Paul and his crush work could be any sterile office. We have no idea what the lab is researching, so why waste so much time showing technicians squirting stuff into test tubes or looking busy at their desks? The only payoff is a moment when Paul strokes a guinea pig.

“Red Flag” may be baggy and solipsistic, but it goes down more easily than “Rubberneck” by viewing romantic disappointment through a comic lens. Here Mr. Karpovsky plays a version of himself, an indie filmmaker named Alex who sets off on a road trip to promote a film (played by “Woodpecker,” an actual Karpovsky movie) after his live-in girlfriend, Rachel (Caroline White), boots him out.

Alex is also a version of Paul, healthier but still depressive. Losing Rachel unmoors him, plunging him into panic about himself and his future. Still, he may be knocked down — like Paul, he has moments of suicidal doubt (he scribbles a farewell note on a pink Post-it) — but he’s not out. He can recycle his pain. He can, that is, make “Red Flag.”

If only “Red Flag” were funnier and tighter and had a sharper idea about what it means to blur the lines between self-interrogation and self-absorption. As it is, the movie throws off too few sparks. Lucky for Alex Karpovsky, he has a white knight, Lena Dunham, to ride to the rescue.